Chevy 427 engine

[Sub-versive]

I have been storing stuff at my parents small farm over the years. I have built up a pile of cr@p.
Well, my folks are now looking to sell the property and are cleaning up. I have scrapped my '77 Sub, '76 Luv, '94 Toy PU, and assorted stuff.
I have an emotional attachment to the '76 PU, but the body is shot on it. I am now debating keeping or selling parts of it.
The one item that is at the core of my internal debate(no pun intended), is the engine. My pops transplanted the powerplant from a '69 Chevy Caprice Kingwood Estate, well he traded building a deck for an engine builder rebuilding and installing the engine. The powerplant still runs even if other parts of the truck don't. I know it could use a freshening up. My dad does not know any details about what was done during the rebuild. I can remember when he picked up the truck and asked Ken, Ken justed smiled and said "You'll be happy." I know from experience that it would do a fourwheel burnout, pull a cement truck out of the mud (at the cost of the TH350 ), and leave jaws on the floor of the Camaro or Corvette driver as they saw taillights. I haven't looked at casting numbers, so I don't have those handy.

So my question is what is a used 427 that was built by Ken Thunderbird of Thunderbird Racing, originally from a '69 Kingwood Estate, worth?